243 neck splitting

I was out shooting my 243 today with my daughter to get ready for deer season and after some of the shot I noticed that a couple of the cases the necks were split at the junction of the shoulder. This is the second time these cases have been fired and this gun. I partial resized them and they are loaded with 39 gr H4350 and a 95Gr Hornady SST and WLR primer in a Winchester case. The are grouping well, but it seems to me something is wrong that the cases are failing this quickly. I am open to any and all advise. I have never seen this happen this quickly before in any of the other guns I reload for.

If you could post a picture of the cases that are splitting and some measurements before firing and afterward it would help to figure out what is happening.

Are the cases of recent manufacture?

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I've had that happen with my 243 Ruger No. 1. Once or twice fired Fed cases. It only happened to a few cases, some would split as you seated the bullet. Never quite figured out how or why that happened . They were 5-10 year old cases, but I've reloaded 50 yr old military brass and not had that happen.

As Truck Driver stated; additional info is needed.

FYI - I had factory 30-06 ammo split necks this year. Groups were great and I was a bit disappointed that I couldn't use the brass. The cartridges were about 8-12 years old and factory fresh as it were...

The primary lesson for me was that un-annealed brass seems to work harden over time. Norma's website states: "The case neck is annealed to become softer. This prevents gas leaks and enables the case to hold the bullet firmly for at least 10 years without cracking as a result of aging material."

The secondary lesson was that "season-cracking" can occur when fumes from solvents (or anything with ammonia) get on the cases. So now gun cleaning and storage of solvents is in a different room than the ammo.

I wonder if the neck of your chamber is on the fat size, and the necks of the case on the thin end? I've seen some case necks have to grow as much as .015" to fill the chamber when fired. So through sizing the necks could split?

If you have other once fired brass from that batch, anneal them first before resizing, trimming and loading them. Wouldn't be surprised at all if that clears it up.

Here are a few pictures. I am not sure if these pictures will help or not.

Looks like work hardened brass to me. I would anneal all the brass that didn't crack before I reloaded it again.

truck driver":3nh16n1r said:

Looks like work hardened brass to me. I would anneal all the brass that didn't crack before I reloaded it again.

Click to expand...

Yep. I can't think of much else that causes split necks other than work hardened brass. 99% of the time brass that I toss is because of split necks and I feel I get really long case life with regular annealing, but eventually brass is wore out and the first thing that shows up is almost always split necks. Hotter loads might be loose primer pockets but in my case the necks give out first.

brass is a mix of copper and zinc, any kind of gas can effect its brittleness, chlorine, methane, even gas coming from a pound of decomposing gunpowder. it could even be improper annealing from the factory, all brass is annealed, most of it is polished afterwards. your best bet is anneal your brass, keep it separate from powder, primers until its loaded. there could be volumes printed on what could be causing it.
RR

adm1977":32o383v7 said:

Here are a few pictures. I am not sure if these pictures will help or not.

Click to expand...

Can you guys see the pics? I still just see the square that says to upgrade to share on 3rd party sites.

Welcome to the new Photobucket. They want you to spend money, or you can't post pictures on any site except for their own.

This thread goes into more detail: https://forum.nosler.com/viewtopic.php?f=3&t=35755&hilit=Photobucket

Before I bought an annealing machine I could feel differences in seating pressures seating bullets on brass fired multiple times, some were less pressure than others and it concerned me so I bought a BenchSource annealer and annealed my brass. Now I feel same seating /consistent pressures while seating bullets compared to before I annealed. This could be the issue with your necks splitting, annealing could fix that issue.

Now I anneal every firing or every two firings.

Not sure what happened to the pictures. They were here then disappeared from photobucket. I have heard about this 3rd party hosting thing and I am not upgrading to allow it. I am either going to try flicker or this imgur that everyone else is using. I think the pictures must have slipped through for a while because they were up for a day or so, but I think I am figured out on what is going on with my brass.

what did you come up with?
RR